import sys
sys.setrecursionlimit(10**7)
def dfs(idx,w):
    if (idx,w) in seen:
        return
    for i in range(idx,N):
        if w + W[i] == total_w/2:
            print("possible")
            exit()
        elif w + W[i] < total_w/2:
            seen.add((i,w))
            dfs(i+1,w+W[i])
            dfs(i+1,w)
        else:
            return

N = int(input())
W = list(map(int,input().split()))
total_w = sum(W)

if total_w/2 != total_w//2:
    print("impossible")
    exit()

idx = 0
w = 0
seen = set([])
dfs(idx,w)
print("impossible")